Question: $ { \left[\begin{array}{rrr}{-1} & {0} & {1} \\ {1} & {0} & {-1}\end{array}\right]+\left[\begin{array}{rrr}{2} & {-1} & {-2} \\ {-2} & {4} & {-1}\end{array}\right] = {?} } $
Answer: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rrr}{-1}+{2} & {0}+{-1} & {1}+{-2} \\ {1}+{-2} & {0}+{4} & {-1}+{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{1} & {-1} & {-1} \\ {-1} & {4} & {-2}\end{array}\right]}$